Why Cutting Carbs Can Quietly Undermine Muscle & Metabolic Health
If you’re lifting weights consistently, prioritizing protein, and still not seeing the muscle or strength gains you expect, you’re not alone. Many women follow all the “right” fitness advice yet feel chronically fatigued, stuck, or frustrated by slow progress. According to Ana Kausel, M.D., a board-certified endocrinologist, there’s one major piece missing from most women’s muscle-building plans.
On the mindbodygreen podcast, Kausel explains that while protein gets most of the attention, carbohydrates are often the overlooked key to building muscle and supporting metabolic health. As someone who taken care of hundreds of women and has navigated her own body composition changes, she’s seen firsthand how carb restriction can quietly undermine strength, energy, and long-term results.
In fact, Kausel estimates that more than 80% of her female patients have cycled through low-carb diets, intermittent fasting, or fasted workouts in the name of fat loss. The intention is good, but the outcome often isn’t. When it comes to muscle, carbs matter more than most women realize.
Why carbs are essential for muscle & metabolism
Carbohydrates are the body’s primary fuel source during resistance training. When you lift weights, your muscles rely on glycogen, the stored form of carbohydrates, to produce force and sustain effort. Without enough carbs, workouts feel harder, strength plateaus faster, and recovery slows.
From a hormonal perspective, chronic carb restriction can also send stress signals to the body. Cortisol levels rise, training capacity drops, and muscle protein breakdown can increase. Over time, this makes it harder to gain lean mass and easier to lose it.
Kausel sees this pattern constantly in her practice. Many women come in eating what looks like a “clean” diet on paper, but are under-fueling relative to their training demands. They’re following trends instead of listening to their physiology.
“If you really want to be strong and you want to do strength training, you need to eat carbohydrates,” she explains on the podcast. The difference, she says, can be dramatic once women stop fearing carbs and start using them strategically.
Why low-carb trends often backfire for women
Low-carb and fasted training approaches are often marketed as metabolic upgrades, but they don’t always align with female physiology, especially for women training hard or navigating hormonal changes.
Kausel notes that many women she works with feel disconnected from hunger cues, energy levels, and performance because they’ve been overriding their bodies for years. Fatigue, stalled strength gains, poor sleep, and inconsistent cycles are common signals that something isn’t working.
Muscle responds best to consistency, adequate fuel, and recovery. When carbs are chronically low, the body simply doesn’t have the resources it needs to adapt. Instead of becoming more efficient, it becomes more stressed.
How to fuel muscle growth more effectively
Kausel doesn’t recommend abandoning balanced eating or loading up on refined carbs. The goal is intentional fueling.
Including carbohydrates around workouts can help support training intensity and recovery. Pairing carbs with protein at meals supports muscle protein synthesis and keeps blood sugar more stable. Whole food sources like fruits, vegetables, legumes, and whole grains can all play a role.
Most importantly, Kausel encourages women to stop treating carbs as something to “earn” and start viewing them as a tool. When fuel matches demand, the body responds.
Here’s how to make carbs work for you:
- Eat carbohydrates regularly, especially on training days.
- Pair carbs with protein to support muscle repair and growth.
- Avoid fasted strength training if muscle is your goal.
- Pay attention to energy, performance, and recovery, not just macros.
- Adjust intake based on training intensity rather than diet trends.
The takeaway
Building muscle as a woman isn’t about pushing harder or cutting more. It’s about aligning your nutrition with what your body is actually asking for. Carbohydrates aren’t the problem; they’re often the missing link.
When you fuel adequately, training feels stronger, recovery improves, and progress becomes sustainable.